Atto 647 is a zwitterionic dye with a net electrical charge of zero. It is a pH sensitive product. While practically stable up to pH 8.5, it slowly degrades at higher pH. Atto 647 is a new label with high molecular absorption (120,000) and quantum yield (0.20) as well as enough Stokes shift between excitation and emission maximum. Atto 647 is characterized by a high photostability and brightness. In addition, this label has good water solubility and low triplet formation ability.
Atto fluorescent labels are designed for high sensitivity applications, including single molecule detection. Atto labels have rigid structures that do not show any cis-trans-isomerization. Thus these labels display exceptional intensity with minimal spectral shift on conjugation.